Udemy coming in at 66% is pretty surprising to me. I personally purchased some 50 courses on there, and am happy with the result (especially owning the course and not having to deal with a subscription), but it is surprising to me that it basically won that market. It isn't all that friendly to course maker iirc. And the course quality varies a lot. Its pricing model is also very shady, giving me the impression that it is a poorly run company.

Of course - youtube is not included; I imagine that'll really skew the graph

edit: shoot, I just checked and I actually purchased 98 courses.